HALF-BRIDGE DRIVER WHICH IS INSENSITIVE TO COMMON MODE CURRENTS

摘要

A half-bridge is made insensitive to transient induced common mode currents in a pair of control lines between a level shifter and a floating driver for a power transistor of the half-bridge by the provision in the receiver portion of the floating driver of a double differential amplifier responsive to the difference between the voltages developed across sense resistors in series with the control lines. The amplifier produces a pair of output voltages for selectively setting and resetting a flip-flop which controls the conductive state of the driven power transistor. The double differential amplifier has an inherent central dead zone, providing noise immunity, and optional clamp means to limit the extremes of the voltages developed across the sense resistors. The transmitter portion of the level shifter contains elements thermally and resistively matched to the receiver for determining the amplitudes of the transmitted control currents.